Tchirikov M, Hecher K, Deprest J, Zikulnig L, Devlieger R, Schröder H J
Division of Experimental Medicine, Department of Obstetrics and Gynecology, Universitäts-Klinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
Ultrasound Obstet Gynecol. 2001 Dec;18(6):656-61. doi: 10.1046/j.0960-7692.2001.00467.x.
To establish by Doppler ultrasound the effects of acute blockage of umbilical cord vessels on the fetal central circulation.
Experimental study in anesthetized pregnant sheep.
In 11 anesthetized pregnant sheep (0.66 of gestation), Doppler velocity profiles and/or venous flow rates were recorded in the ductus venosus, the fetal aorta, the umbilical arteries and the umbilical vein. This involved three phases. In Phase 1, the abdominal wall was closed (n = 9); Phase 2 was during fetoscopy after laparotomy (n = 8); Phase 3 was after coagulation of one of the umbilical arteries (n = 10). As an additional intervention in six fetuses, the umbilical cord was clamped for 5-15 s while blood flow velocity changes in the ductus venosus were observed.
There were no significant differences between Doppler recordings in Phases 1 and 2. During Phase 3, the pulsatility index of the aorta and of the coagulated umbilical artery increased significantly. The umbilical vein blood flow rate was significantly reduced from a median of 408 (range, 243-575) mL/min/kg in Phase 1 to a median of 173 (range, 107-426) mL/min/kg in Phase 3, but the blood flow rate in the ductus venosus (median, 94; range, 56-148 mL/min/kg vs. median, 92; range, 33-237 mL/min/kg) remained unchanged. The ductus venosus/umbilical vein ratio increased from a median of 0.22 (range, 0.13-0.41) to 0.56 (range, 0.17-0.97) (P < 0.05). Compression of the cord (5-15 s) immediately reduced the time averaged maximum velocity in the ductus venosus from a mean of 51 (standard deviation, 11) cm/s to 20 (standard deviation, 6) cm/s (P < 0.001) without significant changes of the velocity profile. However, the pulsatility index increased from a mean of 0.55 (standard deviation, 0.19) to 1.89 (standard deviation, 0.73) (P < 0.001).
Central venous flows in anesthetized fetal sheep are unaffected by laparotomy and hysterotomy. Obliteration of one umbilical artery increases the ductus venosus/umbilical vein volume flow (mL/min/kg) ratio. Compression of the umbilical cord shifts down blood flow velocity profiles in the ductus venosus, and the pulsatility index thus increases.
通过多普勒超声确定脐带血管急性阻塞对胎儿中心循环的影响。
对麻醉的怀孕绵羊进行实验研究。
在11只麻醉的怀孕绵羊（妊娠0.66）中，记录静脉导管、胎儿主动脉、脐动脉和脐静脉的多普勒速度剖面和/或静脉血流速度。这包括三个阶段。在第1阶段，关闭腹壁（n = 9）；第2阶段是在剖腹术后进行胎儿镜检查时（n = 8）；第3阶段是在一条脐动脉凝固后（n = 10）。作为对6只胎儿的额外干预，在观察静脉导管血流速度变化的同时，将脐带夹闭5 - 15秒。
第1阶段和第2阶段的多普勒记录之间无显著差异。在第3阶段，主动脉和凝固的脐动脉的搏动指数显著增加。脐静脉血流速度从中位数408（范围243 - 575）mL/min/kg显著降低至第3阶段的中位数173（范围107 - 426）mL/min/kg，但静脉导管的血流速度（中位数94；范围56 - 148 mL/min/kg对中位数92；范围33 - 237 mL/min/kg）保持不变。静脉导管/脐静脉比率从中位数0.22（范围0.13 - 0.41）增加至0.56（范围0.17 - 0.97）（P < 0.05）。脐带压迫（5 - 15秒）立即将静脉导管中时间平均最大速度从平均51（标准差11）cm/s降低至20（标准差6）cm/s（P < 0.001），速度剖面无显著变化。然而，搏动指数从平均0.55（标准差0.19）增加至1.89（标准差0.73）（P < 0.001）。
麻醉的胎儿绵羊的中心静脉血流不受剖腹术和子宫切开术的影响。一条脐动脉闭塞会增加静脉导管/脐静脉体积流量（mL/min/kg）比率。脐带压迫使静脉导管中的血流速度剖面下移，搏动指数因此增加。
